Transparency mounts



Feb. s, 196s N "QN TRANSPARENCY MOUNTS Filed March 6, 1961 INvEN-roR 4Lfaorwmeo N. AFToN 2 Claims. (Cl. l0-158) The present invention relates to lrn holders and has particular reference to a novel form of mounting for :lilrns of the type commonly ,.nown as color transparencies which are adapted to be inserted in a still projector or viewer. The invention has been designed for use primarily in connection with the mounting of color transparencies of the 36 min. type which, at the present time, are most frequently mounted in holders for lm preservation and viewing purposes but it will be understood that the invention is by no means limited to such use .and iilnt holders constructed in accordance with the principles oi' the invention with or without modification, be employed for mounting pictures of a wide variety of types and sizes. irrespective, however, ci the particular use to which the present invention may be put, the essential features thereof are at all times preserved.

Transparencies of the type with which the present invention is concerned are ordinarily in the iorin of a thin, iiexible, perishable photographic iilrn, either colored or of the black and white variety, and it is present-day practice to mount such transparencies in holders constructed of cardboard, metal, glass, or a combination of such substances, such holders or mounts variously serving manifold purposes such as protection of the lrn from contamination, lending rigidity to the lrn, facilitating storage, filing, cataloging or indexing of the iilrn, rendering the iilrn susceptible to ease of handling, adapting the lrn for use in a still projector, slide viewer or the like, or otherwise enhancing the appearance and utility of the ilrn. Cardboard mounts possess numerous limitations in that they are not durable, are easily bent, aiiord little or no protection to the lrn against the heat generated in high wattage projectors, and frequently lose their shape so that they jam in the projection apparatus. Mounts having glass components are subject to breakage, present especial diiiicnlty in centering the iilrn accurately on or between the glass plates, and are expensive to manuiacture. Metal mounts, while durable, are expensive, heavy, possess sharp corners or edges which damage the lilrn, `and sometimes present objectionable secondary lighting or image efiectsin the projection apparatus. Many ofsuch mounts require special care in assembling the constituent parts thereof, particularly insorar as centering of the lilrn within the viewing opening is concerned, and also insofar as etecting proper margin-shielding or masking of the lni to prevent margin projection in the proiection apparatus or the admission of margin lighting eiiects in the viewer.

The resent invention is designed to overcome the above noted limitations that are attendant upon the construction, assembly and use or" mounts of the character outlined above, and toward this end, it contemplates the provision of a novel form of transparency mount which,

` rigidifying border regions or" the mount, although formed- 3,7%,279 Patented Fein. 5, 1963 in one forni thereof, is constructed entirely or transparent thermoplastic material and which, in other moditied forms thereof, is constructed substantially entirely oi such material, and which, despite the use of transparent material, aliords adequate marginal masking or light intercepting qualities.

rifhe provision of a transparency mount oi the character briefly set forth above being among the principal objects oi the invention, it is another object thereof to provide such a mount which, when the film is assembled therein, presents relatively thin transparent protective panels between which the iiltn is sandwiched in cotnrtensive` relationship, with the panels bearing against the opposite sides of the lm respectively and serving to maintain the iilm flat so that the saine cannot curl or otherwise become deformed and also serving to protect the iilrn against scratching, nlarring or other forms of defacernent, as well as shielding the same against contamination by foreign substances, fingerprints, or the like.

A further object of the invention is to provide a transparency mount of this type'in which the aforementioned film-protecting panels are cornrnon to are integrally fori-ned with a marginal, reinforcing, illm-rnasl ing, border-providing, frame-like portion of slightly greater thickness than the combined thickness of the panels and illtn, this marginal region lending rigidity to the mount as a whole, with the ilrn being so disposed relative to the panels and the marginal thickened portion so that it is completely embedded within the thermoplastic material et the mount and permanently hernietically sealed within the sante.

A similar and related object of the invention is to provide a mount of this character in which the marginal ci transparent material, is so designed or shaped as to present light deilecting and reflecting phenomena whereby beams oi light emanating from the projector or viewer illuminating sonrce will be reflected or detlected i'rorn the surface of the marginal portion or" the mount and thus prevent it rorn being protected directly through this marginal portion so that on the projection screen or in the viewers eye, this marginal portion will present translucent characteristics.

Y et another object of the invention, in a transparency mount of this sort is to provide a structure, the overall width of which is sufliciently srnall that it is capable of use in any of the conventional well-known slide prog'ectors or viewers on the market and in which the surrounding thermoplastic material affords excellent heat shielding characteristics to the illrn so that the amount is suitable for use in connection with so-called high wattage projectors. Y

i The provision of a transparency mount which readily lends itself to large-scale production by a continuous shaping, molding or rolling operation, and which, therefore, may be inode in quantity at a relatively low cost; one which is of unitary construction and which, therefore, is rugged and durable so that it will last indefinitely; one in whic the masking regions thereof are sharply deilned from the viewing regions; one which is of light weight construction; one which is attractive in its appearance and pleasing in its design, and one which other- Wise is well adapted to perform the services required of it are further desirable features which have been borne in mind in the production and development of the present invention.

Other objects and advantages of the invention, not at this time enumerated, will become more readily apparent as the following description ensues.

In the accompanying single sheet of drawing forming a part of this specification, several embodiments of the invention have been shown.

In this drawing:

FIG. l is a perspective view of a transparency mount constructed in accordance with the principles of the present invention;

FIG. 2 is a sectional view taken substantially along the line 2-2 of FIG. l;

FIG. 3 is a sectional view taken substantially along the line 3-3 of FIG. l;

FIG. 4 is a perspective view similar to FIG. 1 showing a slightly modified form of transparency mount constructed in accordance with the principles of the present invention;

FIG. 5 is a sectional view taken substantially along the line 5 5 of FIG. 4;

FIG. 6 is a fragmentary sectional view similar to FIGS. 3 and 5 showing a further modified form of transparency mount;

FIG. 7 is a fragmentary sectional view similar to FIG. 6 of another modified form of transparency mount; and

FIG. 8 is a fragmentary perspective view showing yet another modified form of transparency mount.

Referring now to the drawings in detail and in particular to FIGS. l to 3, inclusive, wherein one form of a transparency mount constructed in accordance with the principles of the present invention has been shown, the mount has been designated in its entirety at 1G and is in the form of a single one-piece, generally at, rectangular body which may be formed of a suitable thermoplastic material having low shrinkage characteristics and capable of withstanding the relatively high heat to which mounts of this type are liable to be subjected when employed in still projectors or slide changers of the type mentioned above, and particularly, projectors of the high wattage type. As will be set forth in detail presently, the body 10 is provided with a central rectangular viewing or picture area l2 and a surrounding marginal masking area 14.

The one-piece body 10 may conceivably be formed by various molding operations, such as compression molding, injection molding, and the like, but the same is particularly suitable for a continuous sheet molding or rolling operation wherein the body is made up from two separately formed sections or laminations, each of which may issue continuously from respective pairs of heating rolls having the necessary surface characteristics to impart to their respective laminations the desired surface contours. The two laminations may be brought together into intimate face-to-face contact while at the same time the various lm fragments which are to be mounted may be accurately positioned or sandwiched between the laminations, and the laminations thereafter pressed together, either under the application of heat or the use of a softening agent or solvent, so as to seal the lm fragments in position between the laminations, and thereafter, the continuous composite structure may be severed successively to produce the individual mounts. The illustration of FIG. 1 is predicated upon such a continuous method of formation of the transparency mount and, accordingly, the theoretical division plane between the two preformed sections has been illustrated in dotted lines and designated at i6, although it will be understood that such a division plane will be scarcely visible in the completed mount.

As best seen in FIGS. 2 and 3, the rectangular picture area 12 is relatively thin and the rectangular dimensions thereof are Isubstantially equal to or slightly less than the rectangular dimensions of the lm fragment 18 associated with the mount. This lm fragment 1S, which may be a 35 mm. cellulose ester derivative ilm element, is positioned between the two picture viewing portions of the preformed transparency mount counterparts, or is otherwise embedded in the thermoplastic material in the central picture viewing region 12 thereof so that a film-like covering or panel extends completely across the rear side of the film element i8 as at 20 and across the front side of the lm element 18 as at 22. Each panel 20 and 22 makes coextensive face-to-face contact with the adjacent surface of the iilm fragment 1S so that air bubbles and the like are completely excluded. When formed by the continuous process outlined above, the film fragment 18 is contained within a sealed pocket 24 of no greater thickness than the thickness of the film fragment but of slightly greater longitudinal and transverse extent so that small clearances will be provided at the ends and sides of the film fragment as indicated at 26 and 28 in FIGS. 2 and 3, respectively, to allow for slight planar expansion and contraction of the film due to differences in the coefficient of expansion of the cellulose ester lm material and of the thermoplastic material from which the body 1t) may be formed.

The body 10 is provided with a rectangular depression in the front face thereof which depression, in itself, affords the picture area 12, and by virtue of such depression the two transparent panels Ztl and 22, together with their interposed lm fragment t8, are offset laterally from the medial plane of the body 1t). The end walls 36 and the side walls 32 of the depression 12 are inclined at a predetermined angle relative to the medial plane of the body 10 so that these side walls 30 and 32, in effect, present a sunken bevelled border for the picture area or depression 12. The specific angle made by these inclined surfaces Sti and 32 relative to the medial plane of the body 10 is not critical beyond a predetermined minimum angle, this angle being such that light rays issuing from a source such as a projector light source and travelling toward the front face of the block 10 normal to the medial plane thereof will strike the surfaces 3l) and 32 at such an oblique angle that almost total reflection of these light rays away from the surfaces 30 and 32 will take place, with very little light entering the transparent thermoplastic media. It is well known that a ray of light in a medium of one refractive index and directed toward a medium of a different refractive index, passes into the second media with refraction, provided the angle of incidence is not too large. If the ray is inclined more and more, however, a position will be reached in which it does not pass into the second medium, but is totally reflected at the surface of separation. The angle at which total reliection takes place is called the critical angle of incidence. In general, total reflection will occur at the boundary separating two media having different refractive indices, when any ray in one medium is directed toward the other medium at an angle of incidence greater than the critical angle. The angle of deviation of the surfaces 3d and 32 from a plane normal to the medial plane of the body l0 should, therefore, be at least as great or slightly greater than the critical angle of incidence for the thermoplastic media relative to air. When such an angle is maintained, substantially all of the light issuing from a source such as the light source of a slide projector will strike the surfaces Si) and 32 and be totally reflected and directed into the picture area 12 instead of being deflected into the body of the thermoplastic material.

The rectangular border region 14 of the body 10 is appreciably thicker than the overall thickness of the picture viewing portion 12 of the body, but the thickness of this border region is held to a predetermined minimum wherein the necessary overall rigidity of the transparency mount is maintained. The rectangular thickened border region 14 provides a frame-like structure having parallel side member 34 and 36, respectively, and parallel end members 3S and 40, respectively.

Still referring to FIGS. 1 to 3, inclusive, the front face of the end members 38 and 40 are formed with a series of adjacent, elongated, parallel, lenticular, ribs 42 of substantially V-shape cross sectional shape and having linear apices. These lenticular ribs are coextensive with the side members 38 and 49 and extend transversely of the body it) as a whole. The iirst or innermost rib 42 of each series of ribs has one face thereof in common with the adjacent inclined surface 30. Similarly, the front faces of the end members 34 and 36 are formed with respective series of ribs 44 which are identical with the ribs 42 both as regards their cross sectional configuration and their spacingjwith the latter ribs 44 bridging the distance between the adjacent innermost ribs 42. The innermost rib 44 of each series has one surface thereof in common with the adjacent inclined surface 32.

The rear faces of the end members 38 and 40, as well as of the side members 34 and 36, are provided with respective series of ribs 46 and 48, respectively. To avoid needless repetition of description, it is deemed sufcient to state herein that the ribs 46 and 48 are similar to the ribs 42 and 44, are similarly disposed on the rear faces of the side and end members, and have their apices lying in the common plane of the outer face of the rear panel 2d. The angle between the adjacent faces of the adjacent ribs 42 may be the same as between the ,adjacent faces of adjacent ribs 44, the angle selected for illustration herein being 45. The angle between the adjacent faces of adjacent ribs 46 may be the same as the angle between adjacent faces of adjacent ribs 48, the selected angle shown herein being 60. The purpose of utilizing different angles will be made clear presently.

When the transparency mount is operatively mounted in a slide projector or viewer, the various ribs 42, 44, 46 and 48 provide, in effect, a series of prisms or lenses by means of which substantial opacity is accorded the border region 14 of the mount 10. Light issuing from the projector source and striking the surfaces 3i) and 32 is, as previously described, directed inwardly toward the picture Vviewing area 12, since it strikes these surfaces at an angle which is less than the critical angle of incidence. The inclination of the side of the individual lenticular ribs 42 and 44 relative to the medial plane of the body 10 is also such that light normal to the body 1i) as a whole will strike these surfaces at an angle which is less than the critical angle of incidence. The reiiected light will be directed to the next adjacent inclined surface and since the angle involved may exceed the critical angle of incidence, some of this light may be deected into the transparent media. However, such deflected light will undergo a subsequent deflection after it passes through the border regions 14 of the body 1) and encounters the interface between the surfaces of the ribs 46 or 43, as the case may be, on the rear face of the body 10 and very little, if any, light will emerge for projection on the screen of the projector. In any event, the lenticular series of ribs on the front and rear faces, respectively, of the body 10 will cooperate with each other to exclude direct passage of light through the border regions 14 and any such light may find a path through the body 10 will be so materially dispersed, broken up, and otherwise reduced in intensity that it will have no appreciable eifect as a projection on the screen.

In the form of the invention shown in FIGS. 4 and the same optical principles of masking obtain as in the form of the invention shown in FIGS. 1 to 3, inclusive. The mount lila is similar in its construction `to the mount 1li and to avoid needless repetition of description, identical characters ofrreference with different suffixes have been applied to the corresponding parts in the two views. In FIGS. 4 and 5, the picture viewing portion 12a remains substantially the same as do the various ribs 42a and 46u on the front and Vrear sides of the body lia, respectively. The ribs 44a and 48a are disposed in parallelism to the ribs 42a: and 44a so that all of the ribs on each side of the mount 10a extend inparallelism. The inclined or bevelled surfaces 30a and 32a which provide a border for the picture viewing panel 22a have not been altered. The optical effect produced by the various ribs 42a, 44a,

. 46a, and 48a varies from the ribs associated with the mount 10a only insofar as directional characteristics of reiiection and deflection are concerned and the overall eifect is to produce a border region 14a which is substantially opaque.

In FIG. 6, wherein a further modied form of transparency mount ltlb has been illustrated, the various lenticular ribs have been omitted and the border regions 14b of the mount 10b have embedded therein a rectangular open frame-like sheet 50h of a substance which is totally opaque, as, for example, metal foil. In this form of the invention, the inclined or bevelled surfaces 30h and 32b remain substantially the same and the inner border of the metal foil or other opaque sheet Stili terminates within the projected lateral confines of the inclined surfaces Stlb and 32h so that these latter inclined surfaces are relied upon to reiiect light and prevent the same from passing through the body 10b at the region just inside the inner margin of the sheet 5G11.

In the form of the invention shown in FIG. 7, a rib structure similar to those shown in FIGS. 1 and 4, respective-ly, may be maintained on the front and rear surfaces of the transparency mount file. However, in the manufacture of the mount, instead of heat sealing the front and rear mount sections together in the border regions 14C thereof, a suitable transparent adhesive cement for a softening agent such ras has been shown at 16C is employed.

In FIG. 8, yet another modiiied form of the invention has been shown wherein the transparency mount is of unitary one-piece transparent thermoplastic construction with the lenticular series of ribs omitted. In this form of the invention, the front fand rear faces of the border regions 14d have been treated :as at 52d and 54d, respectively, to provide -a frosting or similar diffusing eifect on these surfaces to disperse light and render the border regions 14d, as a whole, translucent. The inner margin of the diffused portion 54d falls within the projected lateral confines of the inclined or bevelled surfaces 3i) and 32 and the prism effect of these latter surfaces 30 and 32 may be relied vupon to exclu-de light from passing through the mount 10d in the immediately vicinity o-f the inneredges of the treated surface 54d. Various methods of rendering the surfaces 52d and 54d Vtranslucent are contemplated and among these are sanding or otherwise roughening of these surfaces, spraying them with an opaque or translucent paint, or coating them with a suitable adhesive and thereafter spraying the coated surfaces with a trans-lucent or opaque dispersion of solid particles.

It may be found further desirable, due to manufacturing or other expediencies or to attain different and varying optical effects to form the various lenticular ribs of circular or other cross section as may be desired. Other' modifications are contemplated within the scope of the appended claims.

Having thus described the invention what I claim as new :and desire to secure by Letters Patent is:

1. A transparency mount assembly comprising a rectangular, generally flat body of transparent refractive thermoplastic material having 'a relatively thin centrally disposed rectangular film-viewing area surrounded by a relatively thick masking border area, a rectangular transparency film embedded in said relatively thin filmviewing area and substantially coextensive Witht-he same, the front face of said film-viewing area being bounded by l bevelled surface Iareas which are inclined forwardly and outwardly and intersect the front face of said relatively thick maskingfarea, the angle of inclination of each bevelled surface area relative to :a medial plane of the body being less than the lcritical angle of incidence of the refractory thermoplastic material, and a series of lightdelecting ribs coextensive with the. entire front face of said border area, said ribs being arranged in contiguity and having at sides of opposite inclination relative to a transverse plane of the body, said sides intersecting t0 provide sharp linear crest and trough extremities.

2. A transparency mount assembly fas set forth in ciairn l including, additionally, a series of light-deiecting ribs coextensive with the entire rear face of said border area, sai'd r-ibs being arranged. in contiguity and having fiat sides of opposite inclination relative to a transverse plane of the. body, `said sides intersecting to provide sharp linear crest :and trough extremities.

References Citedv in the ile of this patent UNITED STATES' PATENTS Booher May 12, Bielski Sept. 20, Ditly J'uly 22, wenkkum Mar. 16, Bonnet Mar. 7, Lawrence Mar. 11, Brady Aug. 5,

FOREIGN PATENTS Great Britain Dec. S,

Great Britain May 3, 

1. A TRANSPARENCY MOUNT ASSEMBLY COMPRISING A RECTANGULAR, GENERALLY FLAT BODY OF TRANSPARENT REFRACTIVE THERMOPLASTIC MATERIAL HAVING A RELATIVELY THIN CENTRALLY DISPOSED RECTANGULAR FILM-VIEWING AREA SURROUNDED BY A RELATIVELY THICK MASKING BORDER AREA, A RECTANGULAR TRANSPARENCY FILM EMBEDDED IN SAID RELATIVELY THIN FILMVIEWING AREA AND SUBSTANTIALLY COEXTENSIVE WITH THE SAME, THE FRONT FACE OF SAID FILM-VIEWING AREA BEING BOUNDED BY BEVELLED SURFACE AREAS WHICH ARE INCLINED FORWARDLY AND OUTWARDLY AND INTERSECT THE FRONT FACE OF SAID RELATIVELY THICK MASKING AREA, THE ANGLE OF INCLINATION OF EACH BEVELLED SURFACE AREA RELATIVE TO A MEDIAL PLANE OF THE 